Certain embodiments of the present invention generally relate to a connector for interconnecting coaxial cables and more particularly to a connector having contacts arranged in a strip line geometry. Certain embodiments of the present invention generally relate to a ground shield and center contact arrangement for a connector.
In the past, connectors have been proposed for interconnecting coaxial cables. Generally, coaxial cables have a circular geometry formed with a central conductor (of one or more conductive wires) surrounded by a cable dielectric material. The dielectric material is surrounded by a cable braid (of one or more conductive wires), and the cable braid is surrounded by a cable jacket. In most coaxial cable applications, it is preferable to match the impedance between source and destination electrical components located at opposite ends of the coaxial cable. Consequently, when sections of coaxial cable are interconnected, it is preferable that the impedance remain matched through the interconnection.
Conventional coaxial connectors are formed from generally circular components partly to conform to the circular geometry of the coaxial cable. Circular components are typically manufactured using screw machining and diecast processes that may be difficult to implement. As the difficulty of the manufacturing process increases, the cost to manufacture each individual component similarly increases. Accordingly, conventional coaxial connectors have proven to be somewhat expensive to manufacture. Many of the circular geometries for coaxial connectors were developed based on interface standards derived from military requirements. The more costly manufacturing processes for these circular geometries were satisfactory for low volume, high priced applications, as in military systems and the like.
Today, however, coaxial cables are becoming more widely used. The wider applicability of coaxial cables demands a high-volume, low-cost manufacturing process for coaxial cable connectors. Recently, demand has arisen for radio frequency (RF) coaxial cables in applications such as the automotive industry. The demand for RF coaxial cables in the automotive industry is due in part to the increased electrical content within automobiles, such as AM/FM radios, cellular phones, GPS, satellite radios, Blue Tooth(trademark) compatibility systems and the like. Also, conventional techniques for assembling coaxial cables and connectors are not suitable for automation, and thus are time consuming and expensive. Conventional assembly techniques involve the following general procedure:
a) after sliding a ferrule over the cable, stripping the jacket to expose the outer conductive braid,
b) folding the outer conductive braid back over the ferrule to expose a portion of the dielectric layer,
c) stripping the exposed portion of the dielectric layer to expose a portion of the inner conductor,
d) connecting a contact to the inner conductor, and
e) connecting a contact to the outer conductive braid.
The above-noted procedure for assembling a connector and coaxial cable is not easily automated and requires several manual steps that render the procedure time consuming and expensive.
Today""s increased demand for coaxial cables has caused a need to improve the design for coaxial connectors and the methods of manufacture and assembly thereof.
In accordance with an aspect of the present invention, a coaxial cable connector is provided for interconnecting coaxial cables having center and outer conductors. The connector includes first and second insulated housings matably joined with one another and configured to receive first and second coaxial cables. The insulated housings include cavities that receive first and second center contacts configured to securely attach to center conductors of the respective coaxial cables. First and second outer ground contacts are configured to securely attach to outer conductors of the respective coaxial cables and are securable to the first and second insulated housings, respectively. At least one of the first and second center contacts has a planar body section arranged between planar sides of the first and second outer ground contacts.
In accordance with another aspect of the present invention, the first and second insulated housings include top, bottom and side walls formed in a rectangular shape. The first and second outer ground contacts include a rear wall formed with opposed side walls in a rectangular U-shape and having an open front face inserted over the corresponding insulated housing. The first and second insulated housings, when combined, may define flat opposed walls joining the planar sides of the first and second outer ground contacts. Optionally, the insulated housings may include staggered mating faces.
In accordance with another aspect of the present invention, the center contacts are formed with a blade contact and a receptacle contact. The blade contact is arranged in a contact plane extending parallel to the planar sides of the first and second outer ground contacts. The first and second outer ground contacts and the center contacts cooperate to form a strip line geometry. Optionally, the planar sides of at least one of the first and second center contacts are sandwiched between planar sides of the first and second outer ground contacts. The center and outer ground contacts produce electric fields concentrated in regions on opposite sides of the planar sides of the blade contact. The electric fields extend along an axis perpendicular to the planar sides of the center and outer ground contacts.
In accordance with another aspect of the present invention, a connector is provided comprising matable connector housings connectable to coaxial cables having center and outer conductors. The connector includes center and outer contacts securable to the center and outer conductors of the coaxial cable, respectively. The center and outer contacts are securely retained by the connector housings and are arranged in parallel planes with the center contact being sandwiched between the outer contacts.
Optionally, the outer contacts may be formed with U-shaped rectangular shells joining one another to surround the center contact. The center and outer contacts may cooperate to form a strip line geometry. The electric fields are focused on opposite sides of the center contact and extend in a direction transverse to the parallel planes in which the contacts are arranged.
In accordance with an alternative aspect of the present invention, a coaxial cable connector is provided that comprises a housing having opposite ends configured to be connectable to a pair of coaxial cables. The connector includes a center contact having a planar body. The center contact is configured to be connected to conductors and the pair of coaxial cables. The connector further includes ground contacts configured to be connected to ground conductors in the pair of coaxial cables. The ground and center contacts are retained by the housing and are arranged parallel to one another.
Optionally, the ground contacts may have planar bodies and be located on opposite sides of the planar body of the center contact. The planar bodies of the ground contacts are arranged parallel to the planar body of the center contact.
The pair of coaxial cables each form an electric field that is circumferentially symmetrical about the coaxial cables. The center and ground contacts of the coaxial cable connector form an electric field having an asymmetric distribution about center contact with respect to ground contacts, such that the electric field distribution is transferred from a circumferentially symmetric distribution (about the first coaxial cable) to an asymmetric distribution (about center contact with respect to ground contacts) and back to circumferentially symmetric distribution (about the second coaxial cable). The electric field formed by the ground and center contacts may comprise several shapes, but generally is focused or concentrated in areas extending outward perpendicular to the blade contacts in the coaxial cable connector.
The ground contacts may include body sections arranged parallel to the planar body of the center contact and further include sidewalls arranged perpendicular to the planar body of the center contact, thereby entirely surrounding the center contacts to further control and afford a desirable electric field distribution.
The housing of the connector may be formed with a rectangular body having a recessed slot therein that receives the center contact. The body portion may also include flat opposed sidewalls engaging the ground contacts. The body portion forms a dielectric layer between the center and ground contacts. More generally, the housing may be formed of the dielectric material and shaped with flat exterior walls engaging the ground contacts and an interior cavity receiving the center contact. The exterior walls and interior cavity of the housing are dimensioned relative to one another in order to space the center and ground contacts apart from one another by a predetermined distance. The interior cavity in the housing may represent a slot extending parallel to the exterior walls of the housing. The slot and walls cooperate to hold the ground and center contacts, respectively, in parallel planes.
In accordance with another aspect of the present invention, a ground shield is provided for a coaxial cable connector. The ground shield includes contact shells matable with one another to define a shielded chamber extending along a longitudinal axis of the contact shells. Contact shells include walls entirely surrounding a perimeter of the shielded chamber when the contact shells join one another. At least one contact shell is provided with an open end and a cable retention end located at opposite ends of the shielded chamber. The cable retention end is configured to receive and to be connected to a coaxial cable. The contact shell includes at least one wall and at least one adjacent open side extending between the open end and the cable retention end. The open side is subsequently shielded by a wall on the mating contact shell when the contact shells are joined with one another.
The contact shells may be U-shaped, L-shaped, J-shaped and the like. When formed with a U-shape, each contact shell includes opposed side walls and a connecting wall, with the open side opposing the connecting wall. When the contact shells are joined, the side and connecting walls provide 360xc2x0 C. of shielding around a perimeter of the shielded chamber along the length of the shielded chamber from the open end to the cable retention end. The side walls of a single contact shell are located and extend along opposite sides of the shielded chamber and are lined parallel to one another.
Optionally, a coaxial cable displacement contact may be provided at the cable retention end of at least one contact shell. The coaxial cable displacement contact is configured to engage a conductor of a coaxial cable along a plane extending transverse to, and intersecting, the cable retention end of the corresponding contact shell.